A workshop tutorial with Software tutor, Mike Flowers- looking at particular criteria to develop our design development skills to ensure success in the commercial print process.
Scanned images and digital photographs are most commonly edited in Photoshop.
Opening a new file- sizes, resolutions, 300 dpi for commercial print. For commercial print, 300 dpi is the "cut off" in terms of quality- above this, there is no visible difference- just a larger image size. If you need to enlarge an image, you need to change the resolution to maintain dpi quality (for density of colour, etc).
2400-4000 dpi is typical for scanning 35mm negative images to enlarge and retain quality (when using film cameras).
Image > Mode > Where you convert the colour mode of an image. When you do this, a lot of 'filter' options become no longer available. Photoshop WANTS you to work in RGB.
If you revert to CMYK after you have used said filter techniques, you can retain these features- though CMYK files are much larger than RGB.
Can apply foreground colour quickly and easily using paint bucket and colour picker- hues, CMYK percentages, etc. HSB: Hue, Saturation and Brightness.
RGB FILES
The value of '255' is equal to 100%
Converting over from RGB to CMYK can change the colour DRAMATICALLY. Colour shifts such as these need to be avoided- check the colour before you print!
To do this:
View> Gamut warning (to check that your colours will be available to print in CMYK).
Useful for making adjustments- a quick check whilst working. More control than simply converting to CMYK.
Changing the hue and saturation can restore the RGB image to a more "print-friendly" image.
Image> Adjustments> Replace Colour.
Selectively replace colour- almost like using a magic wand to replace colours in the imahe. "Fuzziness" is like magic wand tolerance. Now, when you alter the saturation it only affects particular elements within the image.
View> Proof Colours- The picture becomes a little duller, the file is now in RGB/8/CMYK format (see page bar header).
This is a preview to see how the image will eventually look when it is converted to CMYK.
This method doesn't give you as much control and freedom over the adjustment of your image as 'replace colour' does.
CREATING SWATCHES
Window> Swatches
To delete swatches, hold down Alt and hover mouse over the swatch to delete (creating a scissor icon).
Colour picker/Colour slides
In Swatch Tab> Menu> Create new swatch.
Ensure your colour is in gamut for printing- the box below, when clicked, will bring the colour into the closest CMYK gamut colour.
Picker colour> Add to swatches button.
Pick colour> OK> Foreground Colour> Drag mouse over swatch palette and click.
Select a colour from your image and select as foreground colour, then click into swatch palette to add to swatches. Selecting RGB colours that insure we can work with CMYK.
SPOT COLOURS
Spot colours are used for economic purposes, branding, and for non-printing colours (such as flourescents, metallics, etc).
Click on colour picker> Colour libraries
Choose the appropriate colour book as discussed with the printer/client. As you scroll up or down, the variety of colour options become visible.
Although it is not visible on screen, if you type the REF number on the keyboard, the colour will be selected in the scroll menu.
Repeat the swatch click from foreground colour for the new swatch. Now applied to swatches.
HOW TO RETAIN THE COLOUR VALUES OF SPOT COLOURS IN PHOTOSHOP WITHOUT CONVERTING
To use this method you must have a B&W image (can make adjustments for a colour image- may need to tweak contrasts, etc.) where you go on to swap the black inks for a spot colour (one colour print job).
Image> Mode> Duotone
Can change the colours (spot colour(s) also available) and duotone curve.
Choose colour library and type REF # of spot colour. The black ink has now been replaced with this colour.
The bar along the bottom shows the greyscale of the original image.
The graph box beside the spot colour box controls the curves- the griding structure dictates the percentage of the ink at the numerical points.
In the top bar (header/name) the image will now be a 'monotone' image.
If you return to Image> Mode You can still change the spot colour.
Changing the duotone, you can select another colour- this ensures that 2 (or more) colours make up the image. Often creates a slight sepia tone...use the curves to apply the colour to different areas in the image.
SECOND SPOT COLOUR SAVE TECHNIQUE (APPLIES FOR BOTH COLOUR AND GREYSCALE)
With RGB the R, G, and B channels are all monochrome, but show where the inks will be focused upon and distributed in the image, along with a single Grey channel.
Channels Palette>
In RGB, the separate channels appear monochrome, but they show the channel info of the colour and where it is stored.
Select items can be saved in channels (an alpha channel- contains information about the selection- looks almost like a stencil).
Also used a channel to restore information about spot colours.
Channel Menu> New spot channel (Have your item selected when applying the colours)
The coloured inks will be printed over the original image. Channels with REF numbers and original channel(s).
Can use paintbrush tools (eraser), etc, to edit the image.
Grey Channel> Menu> New Channel> Gradient Tab (Drag over the image to create gradient)
If you want to use spot varnish finishes, create a spot channel and tell the printer you want this as your varnish- not to be printed at the print finishing stage.
Check your stocks when overprinting colours- applying too much ink to stock could make it too wet, make colours bleed, etc.
"Solidity" when choosing a spot colour determines the opacity over an image.
A very valuable lesson in print and the Photoshop programme software. In the past, I have only really ever used Photoshop for portraiture editing, so this workshop has certainly been invaluable to me, and I look forward to utilising these new techniques and skills as soon as possible.
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